Lack of ethics in business activities should not be treated as a result of coincidence or error,but more often than not as a conscious choice of entrepreneur. Observation of economic prac-tice shows, that part of firms is able to make an effort in order to inquire the possibility of doingthe dishonest activity. Dishonest activity, widely named shady business occurs in the formof: tax avoidance to the detriment of budget and other taxpayers (tax evasion), using of illegalinformation to the detriment of stock-exchange investors (insider trading), corruption to thedetriment of employers by depriving them of potential contracting parties (kickbacks), andprice-fixing, and bidrigging to the detriment of purchasers. The companys ability to avoid thelegal sanctions in consequence of unethical activity can be defined as potential of dishone-sty. Creation and utilization of this potential is conditioned by internal factors, such as: lowethical level of businessman, selection of dishonest collaborators, possession of legal knowledge and team of lawyers or unclear structure of property. The external factors favorable to dishonest behaviours include: setting the firms in foreign countries, lack of experience with the courtsand prosecutors, little repeatability of contacts with deceived customers, customers highlymotivated to conclude an agreement, dispersion and weakness of contracting parties.